Between semiconductor device elements, there is for example, a circuit with a multilevel interconnection. With the growing tendency toward micro-fabrication, development of buried interconnect structures has been in progress. A buried interconnect structure is made as follows: a wiring material is buried, for example, into an interconnect hole such as a groove or hole made in an insulation film, using a damascene process (Single-Damascene technique and Dual-Damascene technique). For example, a copper film is deposited so as to fill a groove in the insulation film by electroplating and the copper film is polished by the CMP (Chemical Mechanical Polishing) method so that a buried interconnect is formed in the insulation film groove.
When a circuit requires a capacitor, an MIM capacitor is formed on an interlayer insulation film. JP-A No. 237375/2001 describes a technique based on a damascene process that the bottom electrode of an MIM capacitor is formed together with an underlying buried copper interconnect and its top electrode is formed together with an overlying buried copper interconnect (see Patent Literature 1).
Patent Literature 1: JP-A No. 237375/2001
In the process of forming the top electrode of an MIM capacitor together with an overlying buried copper interconnect, when the underlying buried copper interconnect is exposed at the bottom of a via (hole) for formation of the overlying buried copper interconnect (the insulation film on the underlying buried copper interconnect is removed), the insulation film on the bottom electrode must remain in place as a capacitor insulation film at the bottom of the hole for formation of the top electrode of the MIM capacitor. For this reason, it is necessary to make a photoresist mask pattern on a semiconductor substrate which covers the region for formation of the top electrode and exposes the region for formation of the overlying buried copper interconnect. In order to make such a photoresist mask pattern, an antireflective coating and a photoresist film must be made all over the surface of the semiconductor substrate before the photoresist film is patterned by photolithography. However, for patterning of the photoresist film, the antireflective coating buried in the via for formation of the overlying buried copper interconnect must be removed. The diameter of the via is relatively small and it is not easy to remove the antireflective coating buried in the via. If an excessive force should be applied to remove it, the side walls of the via could be etched, causing a deterioration in the reliability of the resulting buried interconnect and semiconductor device.